These functions can be used to configure the signature algorithms. One
of them is a string mini-languaging parsing function, which we generally
dislike because it defeats static analysis. However, some dependent
projects (in this case TensorFlow) need it and we also dislike making
people patch.
Change-Id: I13f990c896a7f7332d78b1c351357d418ade8d11
Reviewed-on: https://boringssl-review.googlesource.com/30304
Reviewed-by: Steven Valdez <svaldez@google.com>